x=-1:0.1:1;
y=-1:0.1:1;
[X Y]=meshgrid(x,y);
load Z.txt;
xi=-1:0.01:1;
yi=-1:0.01:1;
[XI YI]=meshgrid(xi,yi);
ZI=interp2(X,Y,Z,XI,YI,'spline');
contour(XI,YI,ZI,40);
hold on;
